1. Field of the Invention
The present invention relates to a data communication system. More particularly, the present invention relates to a variable-size packet Forward Error Correction (FEC) encoding apparatus and method.
2. Description of the Related Art
According to diversification of contents and increases in large-capacity contents such as High Definition (HD) contents and Ultra High Definition (UHD) contents communicated via a data communication network, data congestion has become an increasingly serious issue. Due to such a condition, contents transmitted by a transmitter are not completely transferred to a receiver, and some of the contents are lost en route.
In general, data is transmitted by the unit of packets, and accordingly data loss occurs in the unit of transport packets. Accordingly, when the transport packet is lost in a network, the receiver does not receive the lost transport packet, and thus cannot know the data within the lost transport packet. As a result, user inconvenience in various forms occurs, such as audio signal quality deterioration, video picture quality deterioration, video picture break, caption omission, file loss and the like.
In a technology for recovering data lost in the network, a parity block by a Forward Error Correction (FEC) encoding may be added to a source block including a predetermined number of packets and then transmitted. In general, a size (or length) of data transmitted within the packet (that is, source payload) may have a fixed packet size or a variable packet size. For example, a Moving Picture Experts Group2 (MPEG2) Transport Stream (TS) has a fixed packet size of 188 bytes including a header of 4 bytes and a payload of 184 bytes, but sizes of transport packets are not always the same in a Real-Time Transport Protocol (RTP) or a protocol such as MPEG Media Transport (MMT).
When the variable packet size is applied, the transmitter may add padding data to the data to make sizes of actually transmitted packet data the same and then encode the data. However, in this case, an Application Layer (AL)-FEC (AL-FEC) efficiency is deteriorated due to the addition of the padding data. Further, since the inefficiency increases as amounts of the padding data are larger, a method of configuring an efficient source block in data communication to which the variable packet size is applied and an AL-FEC encoding according to the method are desired.